Topics

Pollination Types

Pollination is the process of transferring pollen grains from the anther (male part of a flower) to the stigma (female part) to enable fertilization and seed formation. Pollination is a crucial step in sexual reproduction in flowering plants (angiosperms), and it can occur in different ways, classified based on the origin of pollen or the mechanism by which pollen is transferred.

Types of Pollination:

Pollination can be broadly classified into two main types:

1.     Self-Pollination (Autogamy):

o   In self-pollination, pollen from the anther of a flower is transferred to the stigma of the same flower or another flower on the same plant.

o   Self-pollination ensures reproductive success, even in the absence of pollinators. However, it reduces genetic diversity because the offspring are genetically similar to the parent plant.

o   Examples of plants that exhibit self-pollination include peas, beans, and wheat.

There are two types of self-pollination:

o   Autogamy: Pollination occurs within the same flower.

o   Geitonogamy: Pollination occurs between different flowers of the same plant.

o  

2.   Cross-Pollination (Allogamy):

o   Cross-pollination occurs when pollen from the anther of one flower is transferred to the stigma of a flower on a different plant of the same species.

o   This type of pollination increases genetic diversity, making the population more adaptable to environmental changes and disease resistance.

o   Cross-pollination relies on external agents, called pollinators, for the transfer of pollen. It can occur through various mechanisms depending on the pollination agent.

There are different types of cross-pollination mechanisms based on the agents involved:

4.               Anemophily (Wind Pollination):

§  In anemophily, pollen is carried by the wind. Wind-pollinated plants usually produce large quantities of lightweight, dry pollen that can be easily transported by air currents.

§  Flowers of wind-pollinated plants are typically small, inconspicuous, and lack nectar. They often have long, feathery stigmas to catch pollen from the air.

§  Examples include maize, rice, and grasses.

§

5.                Entomophily (Insect Pollination):

§  Entomophily involves insects such as bees, butterflies, and beetles as pollinators. Insect-pollinated flowers are usually brightly colored and produce nectar and scent to attract pollinators.

§  The pollen grains of these flowers are sticky or spiny, allowing them to adhere to the body of insects as they move between flowers.

§  Examples of entomophilous plants include sunflowers, roses, and orchids.

§

6.               Zoophily (Animal Pollination):

§  Zoophily refers to pollination by animals, including birds (e.g., ornithophily) and bats (e.g., chiropterophily). These flowers are adapted to attract specific animals and often have specialized features such as tubular shapes or nocturnal blooming.

§  Examples include hummingbird-pollinated flowers like trumpet vine and bat-pollinated plants like baobab.

§  

7.                Hydrophily (Water Pollination):

§  Hydrophily is the transfer of pollen through water. This type of pollination is rare and occurs in aquatic plants where pollen floats on the surface of the water until it reaches the stigma of another flower.

§  Examples of hydrophilous plants include Vallisneria and Zostera (seagrass).